When I was working at Amazon, regardless of how busy I was, I made a point of attending the weekly email marketing best-practices meeting. This open-to-anyone meeting was an opportunity to learn what was working for email marketing, to find out what best practices had been uncovered by the email marketing team, and to see examples of emails that had excelled in terms of open rate, click-through rate and sales.

What were the main takeaways from those meetings? Like everything at Amazon, if you want to know what works, test, test, test.

How Does Email Marketing Subject Line Testing Work?

As far as testing content goes, let’s use subject line testing as an example.

There’s more going on in that subject line than you might think. For example, why start that subject line with a numeral, as opposed to spelling out the word “seven”? The reason is likely because whomever sent that email knew that starting the subject line with a numeral produced better open rates than starting a subject line with a written word. But, if that’s the case, how would they know that? They’d know by A/B testing variations of email subject lines against each other, then examining which subject line drove the highest open rate.

E.g.

“7 Tricks to Help You Get Into Shape for Beach Season.”

Vs.

“Seven Tricks to Help You Get Into Shape for Beach Season.”

Almost all email marketing platforms allow you to test at least two subject lines against each other. (These days, multivariate testing—meaning instead of an A/B test you’re doing an A/B/C/D test, or similar—is ever more common, though a simple A/B test is still an effective tool for improving performance.) By cooking up variations of your subject lines, testing them and tracking which version performs better, you can inform future email marketing best practices, improving your email marketing performance.

But how do you know what to test? That’s easy: test everything. Test starting your subject line with a numeral; test subject line length; test subject line topic; test subject lines with time-sensitive messaging, like “Ending tonight: 60 Percent off Your Favorite Socks”; test subject line punctuation…

Test everything.

Marketing email subject lines aren’t randomly written off the cuff; most likely, they’re a calculated combination of numerals and words, carefully crafted to be a specific word or character count, designed based on prior test results to most effectively persuade you to click “open”.

Now, you may have been told that there are universal best practices for website and email content. And while there are some techniques and strategies that work more often than not, there’s no such thing as a “best practice” that applies to every organization universally, whatever you’ve heard. What works for one company is not guaranteed to work for another.

(That said, by auditing 100 million headlines on Facebook, BuzzSumo produced a fascinating list of headline intro types that drove the most engagement. This is great fodder for spurring content tests of all types. Check it out.)

So how do you know what will work for you and your organization? Test. Test. Test.

Content Testing is a Real-Time Content Audit

Email subject lines represent some of the most basic testable content. When it comes to marketing emails, you can test subject lines, imagery type, imagery position, type of content, length of content… heck, you can even test color of text, flashing text, button text… everything. And if you can, you should.

The same is true for virtually all your marketing copy and content. If your website has the capability, you can run a test that pits a page headline against another. If your website doesn’t allow that kind of A/B testing, experiment with different types of headlines, copy length, button copy, page layout, content topic… everything you can to find out what works best.

By constantly testing your content marketing efforts, you’re effectively conducting an ongoing performance audit in real-time. And the takeaways and learnings from these ongoing tests will have tremendous benefits.

Keep Track of the Results

Here’s the part many content marketers forget: you need to record the results of your tests. This is so you don’t forget what’s been working, yes, but also so you can then test your latest best-performing content against something different that you haven’t yet tried. This type of testing is commonly called “champion versus challenger”, and it’s part of the “test everything” mentality.

Keeping track of your results is also important so that you can share your learnings with your larger team, hopefully improving performance across the board.

Test. Test. Test.

Yes, everyone’s busy, and cooking up multiple versions of email subject lines—or any other type of content—might sound like extra work. But the truth is, by committing to testing your content, whether it’s an email, a blog post, a whitepaper or anything else, you’re likely to learn any number of techniques for improving content performance across the board. And that makes it all worth it.